1. Field of the Invention
The present invention relates generally to audio processing, and more particularly to techniques for reducing reverberation within an acoustic signal.
2. Description of Related Art
Various types of teleconferencing and other hands-free audio devices can suffer from the problem of acoustic reverberation. Reverberation is a delayed and distorted version of an original sound caused by acoustic reflections within the environment surrounding the audio device.
A listener present within the same environment as uttered original speech is generally able to adequately differentiate the original speech from reverberation. However, when captured by a microphone and converted into an electrical signal such as for playback to a remote listener, the reverberation can add significant distortion. When present in the electrical signal, it is difficult for the remote listener to separate the original speech from the reverberation. As a result, the remote listener will hear the original speech, along with a delayed and distorted version of the speech, which reduces intelligibility of the electrical signal and interferes with normal communication.
One attempt at reducing reverberation involves predicting the amount of reverberation based on an estimate of the acoustic environment surrounding the audio device. Typically, this estimate utilizes a transfer function which models the impulse response of the surrounding acoustic environment. Reverberation reduction (referred to herein as dereverberation) is then performed through deconvolution (inverse filtering), whereby the electrical signal is filtered based on the transfer function.
Errors in dereverberation can occur due to the difficulty in forming a transfer function which accurately models the surrounding acoustic environment. Specifically, since the surrounding acoustic environment is rarely fixed, the location and number of sources of reflections are constantly changing. If the transfer function used to model the impulse response of the surrounding acoustic environment is even slightly correct, residual reverberation will remain within the electrical signal. The residual reverberation can interfere with the listening experience, and is annoying. In some instances, errors in the transfer function may result in an increase in the distortion of the electrical signal, rather than a decrease.
It is therefore desirable to provide systems and methods for increasing the quality and robustness of dereverberation in diverse acoustic environments.